Aircraft Air Ejector Boundary Layer Control
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Solution Overview
Problem
Conventional methods for improving the high-lift performance of aircraft are limited by the geometrical constraints of wings and high-lift devices, which restrict the adjustment of leading edge slats and trailing edge flaps for enhanced lift-to-drag ratio and maximum lift coefficient.
Innovation Solution
The implementation of a drag reduction system using an air ejector that discharges an air jet over the upper surface of a trailing edge device, reducing aerodynamic drag and enhancing the lift-to-drag ratio by energizing and streamlining the ambient flow, thereby improving the aircraft's high-lift performance without geometrical limitations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If conventional high-lift devices (leading edge slats and trailing edge flaps) are adjusted within geometrical constraints to improve high-lift performance, then maximum lift coefficient increases, but aerodynamic drag increases significantly
Solution Approach 1:
The patent applies pneumatic principles by using air ejectors that discharge high-speed air jets into the boundary layer over the airfoil surface. This pneumatic action energizes the boundary layer, delays flow separation, and maintains attached flow at higher angles of attack, thereby increasing maximum lift coefficient without the drag penalty of conventional high-lift devices
Solution Approach 2:
The invention changes the physical state and properties of the boundary layer by introducing high-momentum air jets. This parameter change in boundary layer energy and velocity profile allows the flow to remain attached at higher angles of attack, achieving increased lift coefficient without the geometric modifications that would increase drag
2Force
If leading edge slats and trailing edge flaps are deployed to increase lift, then high-lift performance improves, but the lift-to-drag ratio decreases
Solution Approach 1:
The system uses pneumatic air ejectors to energize the boundary layer, allowing the airfoil to achieve higher lift coefficients without the significant drag increase associated with conventional high-lift device deployment. This maintains a more favorable lift-to-drag ratio while improving high-lift performance
Solution Approach 2:
By changing the energy state of the boundary layer through air jet injection, the system achieves better lift-to-drag performance. The parameter change in boundary layer momentum allows delayed flow separation and reduced pressure drag, improving the overall lift-to-drag ratio while maintaining high lift capability
3Quantity of substance
If conventional high-lift systems are used to increase payload capacity, then maximum takeoff weight increases, but the system complexity and geometrical constraints increase
Solution Approach 1:
The patent replaces complex mechanical high-lift systems with a pneumatic boundary layer control system using air ejectors. This simplifies the overall system by eliminating or reducing the need for complex slat and flap mechanisms while achieving the same or better payload capacity through aerodynamic means
Solution Approach 2:
The invention substitutes mechanical high-lift devices (slats and flaps) with a pneumatic control system. This replacement reduces mechanical complexity, moving parts, and geometrical constraints while maintaining or enhancing the ability to increase payload capacity through improved aerodynamic performance
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach results in increased payload capacity, reduced runway length requirements, longer range, and improved fuel efficiency by enhancing the lift-to-drag ratio and maximum lift coefficient, allowing for a reduction in engine size and structural mass.
Implementation Method 1
The air ejector is configured to discharge an air jet from the ejection port in an outboard direction relative to a longitudinal axis of the aircraft and in such a manner that the air jet passes over the upper surface of the trailing edge device
Implementation Method 2
The air jet passes over the upper surface of the trailing edge device, reducing aerodynamic drag and enhancing the lift-to-drag ratio by energizing and streamlining the ambient flow
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A drag reduction system for an aircraft (100) may include an air ejector (300) having an ejection port (318) located between an aft portion (130) of an airfoil main element (122) and a forward portion (202) of a trailing edge device (200). The air ejector (300) may be configured to discharge an air jet (322) from the ejection port (318) in such a manner that the air jet (322) passes over the upper surface (204) of the trailing edge device (200).